ci: add performance test reporting for sysbench

Since analyzing the performance test results via the workflow artifacts
is quite inconvenient (we need to download the artifact, unpack it, look
through results), we need a more human approach to see the test report.
Moreover, it would be cool to see the performance difference between the
commits.

So this patch adds reporting the performance test results to MyTeam chat
and mailing list. Furthermore, the comparison of test results is added
to the report. Seeing the test report in the chat or mail is very simple
and convenient, plus forever results history as a bonus.

The test report looks something like this:

    # Curr:
    #   branch:  add-feature-y
    #   build:   1.2.3-42-g6c71c3901
    #   summary: Add feature Y
    #   machine: x86_64
    #   distrib: ce
    #   gc64:    false
    # Prev:
    #   branch:  add-feature-x
    #   build:   1.2.3-41-g5271240ea
    #   summary: Add feature X
    #   machine: x86_64
    #   distrib: ce
    #   gc64:    false
    +----------------------+----------+----------+----------+
    |Sysbench              | Curr(rps)| Prev(rps)|     Ratio|
    +----------------------+----------+----------+----------+
    |oltp_delete           | 11408.000| 11532.000|     0.989|
    |oltp_insert           | 31455.000| 31322.000|     1.004|
    |oltp_point_select     | 65031.000| 66486.000|     0.978|
    |oltp_read_only        |  1732.000|  1735.000|     0.998|
    |oltp_read_write       |  1211.000|  1196.000|     1.013|
    |oltp_update_index     | 15580.000| 15570.000|     1.001|
    |oltp_update_non_index | 16129.000| 16093.000|     1.002|
    |oltp_write_only       |  4482.000|  4434.000|     1.011|
    |select_random_points  | 18525.000| 18517.000|     1.000|
    |select_random_ranges  |  4364.000|  4331.000|     1.008|
    +----------------------+----------+----------+----------+
    |gmean                 |  9223.593|  9220.182|     1.000|
    +----------------------+----------+----------+----------+

NO_DOC=ci
NO_TEST=ci
NO_CHANGELOG=ci

(cherry picked from commit e2803cb1)